为明确胶原蛋白肽在体外消化后抗氧化活性的变化情况，探讨活性肽消化保护的必要性，本实验以羊皮为原料，制备了分子质量集中在低于1 kDa的羊皮酶解胶原肽，研究胶原肽的基本组成和结构特性与抗氧化活性的关系，评价体外模拟消化前后酶解胶原肽抗氧化活性的变化，结合液相色谱-质谱分析和计算机模拟消化分析胶原肽在消化过程中肽段的变化，并采用肠溶胶囊对胃消化阶段的胶原肽进行保护。结果表明，胶原肽富含脯氨酸，二级结构主要为无规卷曲和β-片层，有利于胶原肽抗氧化活性的发挥。胶原肽的还原力和1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl，DPPH）自由基清除率在消化后下降，而2,2’-联氮-双-(3-乙基苯并噻唑啉-6-磺酸)（2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)，ABTS）阳离子自由基清除率上升，原因是DPPH自由基和ABTS阳离子自由基对抗氧化氨基酸的敏感度不同。此外，胶原肽在胃消化阶段的抗氧化活性明显降低，肠溶胶囊的使用对胶原肽的活性具有明显的保护作用。本研究结果在一定程度上为抗氧化活性肽的消化保护提供了实验依据。

The purpose of this research is to clarify the change in the antioxidant activity of collagen peptides after digestion and to explore the necessity of bioactive peptide protection during digestion. The relationship between the amino acid composition and structural characteristics of collagen peptides prepared from sheepskin with molecular mass < 1 kDa and their antioxidant activity was investigated. Meanwhile, the changes in the antioxidant activity of collagen peptides before and after simulated gastrointestinal digestion were measured. The results of liquid chromatography-mass spectrometry (LC-MS) and in silico simulated digestion were considered together to investigate the changes of the peptides during digestion, and the protective effect of enterosoluble vacant capsules on the gastric digestion of collagen peptides was evaluated as well. The results showed that the collagen peptides were rich in proline, and the major secondary structure components were random coil and β-sheet, which could be beneficial to the antioxidant activity. The reducing power and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity of the peptides decreased after digestion, while the 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation scavenging capacity increased. This may be ascribed to the different sensitivities of DPPH radical and ABTS radical cation to amino acids. Furthermore, the antioxidant activity of the peptides decreased markedly after digestion, but it was significantly protected by enterosoluble vacant capsules. In a certain sense, this study provides an experimental basis for the protection of antioxidant collagen peptides during digestion.